It seems fair to say that the draft withdrawal agreement agreed between negotiators and published this week has not been universally welcomed. In particular the Protocol on Ireland/Northern Ireland has been the source of much criticism. In a detailed briefing by the Institute of Economic Affairs, I described how, if it were to come into effect, this Protocol would effectively rule out an independent trade policy for the UK, and would throw up serious trade barriers between Great Britain and Northern Ireland.

It’s worth reminding ourselves of why this Protocol was thought to be necessary. Our government agreed in December last year to guarantee that there would be no physical infrastructure or related checks and controls at the border between Ireland and Northern Ireland. In order to achieve this they conceded that, unless they could put forward alternative solutions, Northern Ireland would stay in alignment with the rules of the customs union and single market in all areas necessary for north south cooperation, the all-island economy and protection of the Belfast (“Good Friday”) Agreement. It was also stated in the Joint Report that the UK would not allow new regulatory barriers between Great Britain and the United Kingdom. The EU’s interpretation of that was a draft agreement under which, “unless and until” other terms were agreed that would meet the objectives for the Irish border, Northern Ireland would remain in a customs union and regulatory area with the EU. This is what the backstop is.

The facilitated customs arrangement and common rulebook of the Chequers plan were an attempt to provide the alternative arrangement that would mean the backstop would never be activated. When Chequers was roundly rejected by the EU, and the Prime Minister declared after the Salzburg summit that no prime minister could accept the EU’s terms, the negotiators went back into their tunnel and reformulated the backstop so that Northern Ireland and the rest of the UK would be in the same customs territory, and Northern Ireland would retain EU regulations on goods “unless and until” a new agreement could be reached. Mrs May is now satisfied that this is something that a British prime minister can sign up to.

Some of us have long been convinced that keeping the Irish border free of infrastructure could be achieved by way of legal, technical and technological solutions. European customs experts Hans Maessen and Lars Karlsson have confirmed to the Northern Ireland Affairs Committee that this can be done. But the EU negotiators and the Irish government have been adamant that the requirements of EU law mean that only a customs union and regulatory harmonisation on goods can achieve this, as even with a free trade agreement with zero tariffs and quotas, the risk of goods that have not been duly declared for customs purposes or that do not meet EU regulations might cross the border cannot be tolerated. Except, it now transpires, for fish. Because under article 6 of the Protocol, fisheries and aquaculture products will be excluded from the customs union arrangements (and therefore fish caught by British and Northern Irish boats would be subject to tariffs) unless an agreement between the UK and the EU on access to waters and fishing opportunities is reached. But by the EU’s own reasoning, the exclusion of even one product would require a full customs border, to ensure that that product isn’t smuggled in undeclared. Now Irish government and EU negotiators could be forgiven for assuming that the British negotiators will concede on this as they have on almost everything else, and sign away fishing rights to the EU. But they might not, and then we would need a hard border wouldn’t we, and the Protocol would be for nothing? Or could it be, that for fish, as for everything else, it is possible to manage a customs border without physical interventions, and the EU is prepared to take the risk of having to do so in order to leverage access to UK territorial waters.